JP6406109B2 - Phosphor, light emitting device using the same, and method for producing phosphor - Google Patents

Description

  The present invention relates to a phosphor, a light emitting device using the same, and a method for manufacturing the phosphor, and more particularly relates to a nitride phosphor that emits light from green to yellow, a light emitting device using the phosphor, and a method for manufacturing the phosphor.

  A light emitting device capable of emitting light of various hues based on the principle of light color mixing by combining a light source and a wavelength conversion member that can be excited by light from the light source and emit light of a hue different from the hue of the light source Has been developed. For example, primary light from a short wavelength region corresponding to visible light is emitted from the light emitting element from ultraviolet light, and the phosphor is excited by the primary light. As a result, at least a part of the primary light is wavelength-converted, and desired light such as red, blue, and green can be obtained. Further, white color mixture light can be realized by additively mixing these component lights.

  Utilizing this principle, LED lamps using light emitting diodes (hereinafter referred to as “LEDs”) as light sources are used for signal lights, mobile phones, various electrical decorations, in-vehicle displays, various display devices, etc. Is used in many fields. In particular, light-emitting devices that are configured by combining LEDs and phosphors and can emit white light (hereinafter also referred to as “white light-emitting devices”) are actively used in backlights of liquid crystal displays, small strobes, and the like. It has been applied and is spreading. Recently, use in lighting devices has also been attempted. Since the white light emitting device has advantages such as long life and mercury-free, it can reduce the environmental load and is expected as a light source that can replace fluorescent lamps.

  As a structure of a white light-emitting device, the structure which combined LED and yellow fluorescent substance is mentioned (for example, refer patent document 1). Such a light-emitting device can provide white mixed color light by mixing light from the LED and yellow light obtained by wavelength-converting a part of this light with a yellow phosphor. . As a phosphor used in such a light emitting device, a phosphor having a characteristic of being efficiently excited by light having a wavelength of 420 nm to 470 nm emitted from an LED and emitting yellow light is required.

  On the other hand, research to improve the light emission characteristics of white light emitting devices is also actively conducted. For example, in order to increase the brightness of white light, it is important to improve the brightness of each color component light. Therefore, it is preferable to use a phosphor capable of converting the primary light from the LED with high efficiency. Further, in order to improve the color rendering property and color purity of white light, it is important that each component light emits light with a predetermined color. Therefore, it is desirable to use a phosphor having a peak wavelength in a predetermined wavelength range.

  As such a yellow phosphor, a cerium activated yttrium / aluminum / garnet phosphor is known. Also known are phosphors in which a part of Y of cerium-activated yttrium / aluminum / garnet phosphor is substituted with Lu, Tb, Gd, etc., and a part of Al is substituted with Ga or the like. Yes. Such a cerium-activated yttrium / aluminum / garnet phosphor can be adjusted in a wide range of emission wavelengths by adjusting the composition.

  On the other hand, it is known that nitride phosphors different from oxide phosphors such as cerium-activated yttrium / aluminum / garnet phosphors have characteristics not found in other inorganic compounds. In recent years, nitride phosphors composed of ternary or higher elements have been widely studied, and there are compounds that emit light from blue to red when excited by LEDs that emit near-ultraviolet light from visible light. It has been reported.

Moreover, the characteristics of the white light emitting device can be further enhanced by combining phosphors having different emission spectra. For example, in a white light emitting device, a (Sr, Ca) AlSiN ₃ : Eu phosphor, which is a nitride phosphor that emits orange or red light, and a yellow phosphor such as a cerium-activated yttrium / aluminum / garnet phosphor By using in combination, the color rendering properties and the color reproduction range can be improved (see, for example, Patent Document 2).

Alternatively, the color rendering properties and the color reproduction range can be improved by replacing the cerium-activated yttrium / aluminum / garnet phosphor, which is a yellow phosphor, with another phosphor. As such a phosphor, for example, La ₃ Si ₆ N ₁₁ : Ce has been reported (for example, see Patent Document 3).

Japanese Patent No. 3503139 JP 2006-8721 A JP 2008-88362 A

When a La ₃ Si ₆ N ₁₁ : Ce-based phosphor is used in a light-emitting device such as a white light-emitting device, it is required to further improve the light emission characteristics of the phosphor. For example, it is required that the phosphor has higher luminance and can emit fluorescence by excitation light over a wider wavelength range. The present invention has been made in view of such a background, and an object of the present invention is to provide a phosphor capable of improving luminance and capable of generating fluorescence by excitation light over a wide wavelength range.

The present inventors use BaF ₂ and / or SrF ₂ as a fluxing agent when manufacturing a La ₃ Si ₆ N ₁₁ : Ce-based phosphor, whereby the luminance of the phosphor is improved and the phosphor Found that fluorescence can be generated by excitation light over a wide wavelength range, and the present invention has been completed.

According to the first aspect of the present invention, a phosphor represented by the general formula La _x Ce _y Si ₆ N _{8 + x + y} (where 2.0 ≦ x ≦ 3.5, 0 <y ≦ 1.0) In the wavelength region of 400 to 510 nm, containing Ba and / or Sr at 10 to 10000 ppm, the first wavelength and the second wavelength at which the excitation intensity is 70% of the maximum value exist, and the second wavelength is the first wavelength. A phosphor longer than one wavelength and having a difference between the first wavelength and the second wavelength of 70 nm or more is provided.

According to a second aspect of the present invention, a phosphor represented by the general formula La _x Ce _y Si ₆ N _{8 + x + y} (where 2.0 ≦ x ≦ 3.5, 0 <y ≦ 1.0) A fluorescence containing Ba and / or Sr of 10 to 10000 ppm and having a minimum value of excitation intensity in a wavelength range of 350 to 450 nm being 50% or more of a maximum value of excitation intensity in a wavelength range of 400 to 510 nm. A body phosphor is provided.

  According to the third aspect of the present invention, there is provided a light-emitting device including an excitation light source that emits light in an ultraviolet region to a blue region and the above-described phosphor.

According to the fourth aspect of the present invention, the phosphor represented by the general formula La _x Ce _y Si ₆ N _{8 + x + y} (where 2.0 ≦ x ≦ 3.5, 0 <y ≦ 1.0) A manufacturing method, wherein La, Ce, and Si alone, oxides, nitrides, carbonates, phosphates, silicates or halides are weighed so as to have a stoichiometric ratio of the composition of the phosphor. A step of obtaining a raw material mixture by grinding and mixing with at least BaF ₂ and / or SrF ₂ as a fluxing agent, a step of firing the raw material mixture in a reducing atmosphere to obtain a fired product, and grinding the fired product to obtain a powder Obtaining a phosphor in the form of a material.

  Since the phosphor according to the present invention has the above characteristics, it has an advantage that the luminance is improved and fluorescence can be generated by excitation light over a wide wavelength range. In addition, the light emitting device according to the present invention can realize excellent light emission characteristics due to the above characteristics. Furthermore, the method for producing a phosphor according to the present invention can provide a phosphor having high luminance and capable of generating fluorescence by excitation light over a wide wavelength range due to the above characteristics.

FIG. 1 is a schematic cross-sectional view of a light emitting device according to an embodiment of the present invention. FIG. 2 is an emission spectrum of the phosphors of the examples and comparative examples of the present invention. FIG. 3 shows excitation spectra of the phosphors of the examples and comparative examples of the present invention. FIG. 4 is an SEM image of the phosphor of Example 1. FIG. 5 is an SEM image of the phosphor of Comparative Example 1. FIG. 6 shows emission spectra of the light emitting devices of the examples and comparative examples of the present invention.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. However, the embodiment described below exemplifies a phosphor for embodying the technical idea of the present invention, a method for manufacturing the same, and a light emitting device using the phosphor. The present invention is not limited to the light emitting device using the phosphor and its manufacturing method and the phosphor.

  In this specification, the relationship between the color name and chromaticity coordinates, the relationship between the wavelength range of light and the color name of monochromatic light, and the like comply with JIS Z8110. Specifically, 380 nm to 410 nm is purple, 410 nm to 455 nm is blue purple, 455 nm to 485 nm is blue, 485 nm to 495 nm is blue green, 495 nm to 548 nm is green, 548 nm to 573 nm is yellow green, 573 nm to 584 nm is yellow, 584 nm to 610 nm is yellowish red, and 610 nm to 780 nm is red.

[Phosphor]
The phosphor according to the present embodiment is represented by the general formula La _x Ce _y Si ₆ N _{8 + x + y} (where 2.0 ≦ x ≦ 3.5, 0 <y ≦ 1.0). The phosphor according to the present embodiment contains 10 to 10,000 ppm of Ba and / or Sr. In addition, when a fluorescent substance contains both Ba and Sr, the sum total of content of Ba and Sr shall be 10-10000 ppm. When the content of Ba and / or Sr is 10 ppm or more, the light emission characteristics of the phosphor can be improved. When the content of Ba and / or Sr is 10,000 ppm or less, the luminance of the phosphor can be increased. The content of Ba and / or Sr is preferably 500 to 10,000 ppm. When the content of Ba and / or Sr is within the above range, the light emission characteristics of the phosphor can be further improved. The Ba content is more preferably 500 to 2000 ppm, and the Sr content is more preferably 500 to 5000 ppm. In the present specification, “ppm” means a weight ratio. It is considered that at least a part of Ba and / or Sr contained in the phosphor is present by replacing a part of the La site in the above composition formula. In addition, it is considered that a part of Ba and / or Sr contained in the phosphor may form a compound with F and exist as an impurity phase. The phosphor according to the present embodiment has a first wavelength and a second wavelength in which the excitation intensity is 70% of the maximum value in a wavelength range of 400 to 510 nm, and the difference between the first wavelength and the second wavelength is 70 nm. That's it. In this specification, the “second wavelength” is longer than the “first wavelength”. That is, in the above wavelength region of the excitation spectrum, the excitation intensity that maximizes the excitation intensity is set to 100%, and the longest wavelength among the wavelengths that becomes 70% is set as the “second wavelength”, and the next longer wavelength is set to “ First wavelength ”. For the phosphor according to this embodiment, the wavelength at which the excitation intensity is maximum is about 450 nm. When the difference between the first wavelength and the second wavelength is 70 nm or more, fluorescence can be generated by excitation light over a wide wavelength range, and therefore, it can be used in combination with a wide variety of excitation light sources. The difference between the first wavelength and the second wavelength is preferably 80 nm or more. When the wavelength difference is 80 nm or more, it can be used in combination with a wider variety of excitation light sources.

  The difference between the first wavelength and the second wavelength is an index indicating the width of the wavelength region of the excitation spectrum (excitation spectrum width) having an excitation spectrum intensity peak near 450 nm. A larger difference between the first wavelength and the second wavelength means that the width of the excitation spectrum having an excitation spectrum intensity peak near 450 nm is larger. On the other hand, the emission spectrum of a light-emitting element that emits light from the ultraviolet region to the blue region usually has an intensity peak near a wavelength of 450 nm. Accordingly, when a light emitting element that emits light in the ultraviolet region to the blue region is used as the excitation light source, the phosphor has a wider wavelength range as the difference between the first wavelength and the second wavelength is larger, that is, the width of the excitation spectrum is larger. Light from the light emitting element can be converted into excitation light. In addition, as the ratio of the minimum value of the excitation intensity in the wavelength range of 350 to 450 nm increases with respect to the maximum value of the excitation intensity in the wavelength range of 400 to 510 nm, the phosphor emits light from the light emitting element over a wider wavelength range. It can be converted into excitation light. In the wavelength region of 350 to 450 nm, the minimum value of excitation intensity is 50% or more, preferably 60% or more of the maximum value of excitation intensity in the wavelength region of 400 to 510 nm. When the ratio of the minimum value of the excitation intensity to the maximum value of the excitation intensity is within the above range, the phosphor can be excited more strongly by the excitation light. It is expected that the phosphor having the excitation spectrum as described above can improve the light emission efficiency of the light emitting device in which the light emitting element that emits light in the ultraviolet region to the blue region and the phosphor according to the present invention are combined.

x is preferably 2.0 <x <3.3, and more preferably 2.0 <x <3.0. When the value of x is 2.0 or more, preferably greater than 2.0, a phosphor having the desired composition can be obtained efficiently. When manufacturing the phosphor, in addition to the phosphor having the target composition, a phosphor having a composition different from the target composition (for example, LaSi ₃ N ₅ ) may be obtained as a by-product. In such a case, an operation for separating the phosphor having the target composition from the phosphor having the other composition by a method such as classification is separately required. On the other hand, by setting the value of x to 2.0 or more, a phosphor having a target composition can be easily obtained with high probability. This eliminates the need for additional operations such as classification. The value of x is 3.5 or less, preferably less than 3.3, more preferably less than 3.0. When the value of x is 3.5 or less, it is possible to prevent LaN, which is a raw material of La, from remaining in the phosphor. As a result, it is possible to obtain a phosphor having a target composition and thus excellent characteristics with high efficiency. When the value of x is within the above range, La ₃ Si ₆ N ₁₁ : Ce of the target phase can be obtained efficiently, and the element distribution containing Ce of the activator becomes uniform, improving the characteristics of the phosphor. Can be made.

  y is preferably 0 <y <0.8, more preferably 0 <y <0.5. By adding cerium as an activator, light emission of a target wavelength can be obtained. When the value of y is 1.0 or less, preferably less than 0.8, more preferably less than 0.5, the activator cerium elements can be prevented from interfering with each other and have high luminance. A phosphor can be obtained.

  The phosphor according to the present embodiment preferably contains 10 to 10000 ppm of F. When the content of F is within the above range, a phosphor having even higher emission characteristics can be obtained. Further, the content of F is more preferably 10 to 1000 ppm, and further preferably 50 to 200 ppm.

  It is preferable that at least a part of the phosphor according to this embodiment has a crystal phase. When the phosphor is amorphous such as a glass body, since the amorphous structure is non-uniform, the component ratio in the phosphor may be non-uniform, thereby resulting in non-uniform chromaticity. There is a fear. In order to avoid non-uniform chromaticity, it is necessary to strictly control the reaction conditions in the production process to be uniform. On the other hand, when at least a part of the phosphor has a crystal phase, it is easy to make the component ratio in the phosphor uniform, so there is no need to strictly control the reaction conditions, and uniform chromaticity can be achieved. A phosphor having the same can be obtained. In addition, when at least a part of the phosphor has a crystal phase, the phosphor can be obtained in the form of a powder or a particle having a crystal phase instead of a glass phase, and thus manufacturing and processing are easy. Such a phosphor can be uniformly dissolved in an organic medium, and preparation of a light emitting plastic, a polymer thin film material, and the like can be easily realized. The phosphor according to the present embodiment preferably has a crystal phase at least 50% by weight or more, more preferably 80% by weight or more. In the present specification, the “crystal phase” means a crystal phase having luminescence. When 50% by weight or more of the phosphor has a crystal phase, more excellent light emission characteristics can be obtained. The higher the ratio of the crystal phase in the phosphor, the higher the luminance of the phosphor and the light emission characteristics. Moreover, the higher the ratio of the crystal phase in the phosphor, the higher the processability of the phosphor. Therefore, when 80% by weight or more of the phosphor has a crystal phase, it is possible to obtain a phosphor having excellent light emission characteristics and excellent workability.

  Considering mounting in a light emitting device, the average particle size of the phosphor is preferably 15 μm to 40 μm, more preferably 20 μm to 40 μm. When the average particle diameter of the phosphor is within the above range, the light absorption rate and the conversion efficiency can be further increased. Moreover, when the average particle diameter of the phosphor is 20 μm or more, formation of aggregates can be effectively suppressed. In addition, in the phosphor, it is preferable that the frequency distribution of the phosphor having the above-described average particle size is high. Further, the particle size distribution of the phosphor is preferably distributed in a narrow range. As described above, by using a phosphor having a small variation in particle size and particle size distribution and optically excellent characteristics, a light emitting device having a good color tone in which color unevenness is further suppressed can be obtained.

  In the present specification, the “average particle diameter” means an average particle diameter measured by a pore electrical resistance method (electric detection zone method) based on the Coulter principle. The pore electrical resistance method is a particle measurement method using electrical resistance. Specifically, the phosphor is dispersed in an electrolyte solution, and fluorescence is generated based on the electrical resistance generated when passing through the pores of the aperture tube. This is a method for determining the particle size of the body.

[Phosphor production method]
Below, an example of the manufacturing method of the fluorescent substance concerning this embodiment is explained. The phosphor manufacturing method according to the present embodiment includes La, Ce, and Si as simple substances, oxides, nitrides, carbonates, phosphates, silicates, or halides. A step of obtaining a raw material mixture by weighing to a stoichiometric ratio and pulverizing and mixing with at least BaF ₂ and / or SrF ₂ as a flux agent, and a step of baking the raw material mixture in a reducing atmosphere to obtain a fired product And a step of pulverizing the fired product to obtain a powdered phosphor.

First, as a raw material, a simple substance of La, Ce and Si, an oxide, a nitride, a carbonate, a phosphate, a silicate, or a halide is represented by a general formula La _x Ce _y Si ₆ N _{8 + x + y} (in the formula, 2. Weigh so that the stoichiometric ratio of the phosphor composition represented by 0 ≦ x ≦ 3.5, 0 <y ≦ 1.0).

As a raw material for La, nitrides, oxides and the like are preferably used, but other compounds or simple substances can also be used. When La nitride or a simple substance is used as a raw material, the amount of oxygen element contained in the obtained phosphor can be reduced, and a phosphor having even higher characteristics can be obtained. Examples of the raw material of La include LaN, La ₂ O ₃ , LaSi, LaSi _{2 and the} like. As a raw material of La, one type of raw material may be used alone, or two or more types of raw materials may be used in combination.

  As a raw material for Ce as an activator, nitrides, oxides, and the like are preferably used, but other compounds or simple substances can also be used. When Ce nitride or simple substance is used as a raw material, the amount of oxygen element contained in the obtained phosphor can be reduced, and a phosphor having even higher characteristics can be obtained. Examples of the raw material of Ce as an activator include halides, carbonates, phosphates, silicates, and the like. When cerium fluoride, which is a fluoride, is used as a raw material for Ce, which is an activator, cerium fluoride functions not only as a raw material for a phosphor but also as a flux agent. Therefore, it is preferable to use cerium fluoride as a raw material for Ce. As the Ce raw material, one kind of raw material may be used alone, or two or more kinds of raw materials may be used in combination.

As a raw material of Si, it is preferable to use a nitride or an oxide, but an imide compound, an amide compound or the like can also be used. When Si nitride or a simple substance is used as a raw material, the amount of oxygen element contained in the obtained phosphor can be reduced, and a phosphor having even higher characteristics can be obtained. Examples of the Si raw material include Si ₃ N ₄ , SiO ₂ , and Si (NH) ₂ . On the other hand, even when only Si is used, it is possible to synthesize an inexpensive phosphor with good crystallinity. The purity of the Si raw material is preferably 2N or more, but may contain different elements such as Li, Na, K, and B. Furthermore, a part of Si may be replaced with Al, Ga, In, Tl, Ge, Sn, Ti, Zr, Hf, or the like. As the Si raw material, one kind of raw material may be used alone, or two or more kinds of raw materials may be used in combination.

Further, in addition to the above-described raw materials, a fluxing agent having a function of generating a liquid phase at a firing temperature described later and promoting the reaction is added. By adding a fluxing agent, the luminance of the phosphor can be improved, and fluorescence can be emitted by excitation light over a wide wavelength range. BaF ₂ and SrF ₂ can be used as the fluxing agent. In the method according to this embodiment, one type of flux agent may be used alone, or two types of flux agents may be used in combination. The content of the fluxing agent in the raw material mixture is preferably 0.01 to 15.0% by weight. When the content of the fluxing agent is 0.01% by weight or more, it is possible to obtain a phosphor having even more excellent light emission characteristics. When the content of the fluxing agent is 15.0% by weight or less, a phosphor having higher luminance can be obtained. Furthermore, in addition to BaF ₂ and / or SrF ₂ , alkali metal halides and / or halides of alkaline earth metals other than Ba and Sr may be used as the fluxing agent.

Each weighed raw material is ground and mixed with at least BaF ₂ and / or SrF ₂ as a fluxing agent to obtain a raw material mixture. The pulverization and mixing of each raw material can be performed dry or wet using a mixer. For pulverization and mixing, in addition to ball mills commonly used in industry, a pulverizer such as a vibration mill, roll mill, jet mill, and mortar-pestle is combined with a mixer such as a ribbon blender, V-type blender, and Henschel mixer. Can be done. The specific surface area of the raw material can be increased by grinding the raw material. In addition, in order to keep the specific surface area of the raw material powder within a certain range, a wet classifier such as a sedimentation tank, a hydrocyclone, and a centrifugal separator that are usually used industrially, and a dry classifier such as a cyclone and an air separator are used. Classification is also possible. When the raw material is unstable in the air, it may be pulverized and mixed in a glove box with an argon atmosphere or a nitrogen atmosphere. By performing pulverization and mixing in this manner, a raw material mixture is obtained.

Next, the raw material mixture is baked in a reducing atmosphere according to the procedure described below to obtain a baked product. First, the above-mentioned raw material mixture is packed in a crucible such as SiC, quartz, alumina, or BN, and fired in a reducing atmosphere such as N ₂ or H ₂ . Firing can also be performed under an argon atmosphere, an ammonia atmosphere, a carbon monoxide atmosphere, a hydrocarbon atmosphere, or the like. The firing is preferably performed at a temperature of 1000 to 2000 ° C. for 1 to 30 hours. The firing pressure is preferably from atmospheric pressure to 10 atmospheres. Firing can be performed in a tubular furnace, a high-frequency furnace, a metal furnace, an atmosphere furnace, a gas pressurizing furnace, or the like. By firing in this way, a fired product is obtained.

  Next, the obtained fired product is pulverized to obtain a powdered phosphor. The powdered phosphor obtained by pulverization may be dispersed in water and then recovered by solid-liquid separation to remove impurities. Solid-liquid separation can be performed by industrially used methods such as filtration, suction filtration, pressure filtration, centrifugation, and decantation. The phosphor recovered by the solid-liquid separation can be dried using an industrially commonly used apparatus such as a vacuum dryer, a hot air heating dryer, a conical dryer, a rotary evaporator and the like. Further, by treating the phosphor with an acidic solution, portions other than the target crystal phase can be removed, and the content of the impurity phase contained in the phosphor can be reduced. As a result, the luminous efficiency of the phosphor can be further improved.

[Light emitting device]
Hereinafter, an example of a light emitting device equipped with the phosphor according to the present embodiment will be described. The light emitting device according to this embodiment includes an excitation light source that emits light in the ultraviolet region to the blue region, and the phosphor according to the present invention. In the light emitting device according to the present embodiment, the phosphor and the excitation light source emit light by absorbing a part of the light emitted from the excitation light source, and the light from the excitation light source and the light from the phosphor are emitted from the light emitting device. The arrangement of the phosphor and the excitation light source is not limited to a specific form as long as it can be taken out. Examples of the light emitting device include a lighting device such as a fluorescent lamp, a display device such as a display and a radar, a backlight for liquid crystal, and the like. Further, as the excitation light source, it is preferable to use a light emitting element that emits light in a short wavelength region from near ultraviolet to visible light, for example, an LED. In particular, a semiconductor light emitting element is preferable because it is small in size, has high power efficiency, and emits brightly colored light. As another excitation light source, a mercury lamp or the like used for an existing fluorescent lamp can be appropriately used.

  There are various types of light-emitting devices equipped with a light-emitting element as an excitation light source, such as a so-called bullet type and surface mount type. In this embodiment, a surface-mounted light emitting device will be described with reference to FIG.

  FIG. 1 is a schematic cross-sectional view of a light emitting device 100 according to the present embodiment. The light emitting device 100 according to the present embodiment includes a package 40 having a recess, a light emitting element 10 as an excitation light source, and a sealing member 50 that covers the light emitting element 10.

  The light emitting element 10 is disposed on the bottom surface of a recess formed in the package 40, and is electrically connected to a pair of positive and negative lead electrodes 20, 30 disposed in the package 40 by a conductive wire 60.

  The sealing member 50 is filled in the recess so as to cover the light emitting element 10. The sealing member 50 includes a phosphor 70. The sealing member 50 protects the light emitting element 10 and other members from the external environment, and also functions as a wavelength conversion member.

  One end of the pair of positive and negative lead electrodes 20, 30 is exposed on the outer surface of the package 40. The light emitting device 100 emits light upon receiving power supply from the outside via the lead electrodes 20 and 30. Below, each member which comprises the light-emitting device which concerns on this embodiment is demonstrated.

(Light emitting element)
The light emitting element 10 can emit light from the ultraviolet region to the visible light region. The peak wavelength of light emitted from the light emitting element 10 is preferably 240 nm to 520 nm, and more preferably 420 nm to 470 nm. As the light emitting element 10, for example, it may be a nitride semiconductor device _{(In X Al Y Ga 1-} X-Y N, 0 ≦ X, 0 ≦ Y, X + Y ≦ 1). By using a nitride semiconductor element as the light-emitting element 10, a stable light-emitting device that is resistant to mechanical shock can be obtained.

(Sealing member)
In the light emitting device 100, the sealing member 50 is filled so as to cover the light emitting element 10 placed in the recess formed in the package 40. As the sealing member 50, a translucent resin or glass can be used. In consideration of ease of manufacture, the sealing member 50 is preferably a translucent resin. As the light-transmitting resin, a silicone resin composition is preferably used, but an insulating resin composition such as an epoxy resin composition or an acrylic resin composition can also be used. The sealing member 50 includes a phosphor 70. The sealing member 50 can further include an additive member as appropriate. For example, when the sealing member 50 includes a light diffusing material, the directivity from the light emitting element 10 can be relaxed and the viewing angle can be increased.

(Phosphor)
The phosphor 70 in the present embodiment includes the phosphor according to the present invention described above. The phosphor 70 absorbs part of the light emitted from the excitation light source (light emitting element 10) and emits light. In the light emitting device 100 shown in FIG. 1, the phosphor 70 is blended so as to be partially unevenly distributed in the sealing member 50. By including the phosphor 70, the sealing member 50 functions not only as a member for protecting the light emitting element 10 and the phosphor 70 from the external environment but also as a wavelength conversion member. As shown in FIG. 1, by placing the phosphor 70 close to the light emitting element 10, the wavelength of light from the light emitting element 10 can be efficiently converted, and the light emission efficiency of the light emitting device 100 is further improved. be able to. In addition, arrangement | positioning of the wavelength conversion member containing the fluorescent substance 70 and the light emitting element 10 is not limited to the form which arrange | positions these close to each other, The influence which the heat | fever which the light emitting element 10 emits has on the fluorescent substance 70 is exerted. In consideration, the light-emitting element 10 and the wavelength conversion member including the phosphor 70 can be arranged with a space therebetween. In addition, by causing the phosphor 70 to be distributed almost uniformly in the sealing member 50, it is possible to obtain a light emitting device that emits light with small color unevenness.

  In the light emitting device, one type of phosphor may be used alone, or two or more types of phosphor may be used in combination. For example, in the light emitting device according to the present embodiment, in addition to the combination of the light emitting element that emits blue light and the phosphor according to the present invention, the phosphor that emits red light is used in combination, thereby providing excellent color rendering. White light can be obtained.

The red phosphor emitting red _{light, (Ca 1-x Sr x} ) AlSiN 3: Eu (0 ≦ x ≦ 1.0) or _{(Ca 1-x-y Sr} x Ba y) 2 Si 5 N 8: Nitride phosphors such as Eu (0 ≦ x ≦ 1.0, 0 ≦ y ≦ 1.0, x + y ≦ 1.0), K ₂ (Si _1-ab Ge _a Ti _b ) F ₆ : Mn ( Halide phosphors such as 0 ≦ a ≦ 1, 0 ≦ b ≦ 1, a + b ≦ 1.0) can be used in combination with the phosphor according to the present invention. By using these phosphors that emit red light in combination, the full width at half maximum of the component light corresponding to the three primary colors can be widened, so that white light richer in warm colors can be obtained.

Further, as a red phosphor, Mn ⁴⁺ activated Mg fluorogermanate phosphor (3.5MgO.0.5MgF ₂ .GeO ₂ : Mn ⁴⁺ ) or M ¹ ₂ M ² F ₆ : Mn ⁴⁺ (M ¹ = Li ⁺ , Na ⁺ , K ⁺ , Rb ⁺ , Cs ⁺ , NH ₄ ⁺ ; M ² = Si, Ge, Sn, Ti, Zr) can also be used. By using these red phosphors together, the half-value width of the component light corresponding to the three primary colors can be narrowed, so white light with higher color reproducibility can be obtained when used as a light source for a liquid crystal backlight unit. It is done.

Other examples of phosphors that can be used in combination include phosphors that emit red light, such as (La, Y) ₂ O ₂ S: Eu, Eu-activated oxysulfide phosphors, (Ca, Sr) S: Eu. Eu-activated sulfide phosphors such as (Sr, Ca, Ba, Mg) ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu, Mn-activated halophosphate phosphors such as Eu and Mn, Lu ₂ CaMg ₂ (Si , Ge) ₃ O ₁₂ : Ce-activated oxide phosphor such as Ce, and Eu-activated oxynitride phosphor such as α-sialon can be used.

  In the light emitting device according to this embodiment, a green phosphor and a blue phosphor can be further combined and used. By further adding a phosphor that emits green light or a phosphor that emits blue light having an emission peak wavelength different from that of the phosphor according to the present invention, color reproducibility and color rendering can be further improved. Further, color reproducibility and color rendering can be improved by adding a phosphor that emits blue light by absorbing ultraviolet light and combining a light emitting element that emits ultraviolet light instead of a light emitting element that emits blue light.

Examples of green phosphors that emit green light include silicate phosphors such as (Ca, Sr, Ba) ₂ SiO ₄ : Eu, Ca ₃ Sc ₂ Si ₃ O ₁₂ : Ce, and Ca ₈ MgSi ₄ O ₁₆ Cl. _2-δ : Chlosilicate phosphor such as Eu, Mn (0 ≦ δ ≦ 1.0), (Ca, Sr, Ba) ₃ Si ₆ O ₉ N ₄ : Eu, (Ca, Sr, Ba) ₃ Si _{6 O 12 N 2: Eu, (} Ca, Sr, Ba) Si 2 O 2 N 2: Eu, CaSc 2 O 4: Ce, Si 6-z Al z O z N 8-z: Eu (0 <z ≦ 4 .2) Oxynitride phosphors such as β-sialons, etc., Ce-activated aluminate phosphors such as (Y, Lu) ₃ (Al, Ga) ₅ O ₁₂ : Ce, SrGa ₂ S ₄ : Eu, etc. Eu-activated sulfide phosphors can be used.

Examples of blue phosphors emitting blue light include (Sr, Ca, Ba) Al ₂ O ₄ : Eu, (Sr, Ca, Ba) ₄ Al ₁₄ O ₂₅ : Eu, (Ba, Sr, Ca). MgAl ₁₀ O ₁₇ : Eu, BaMgAl ₁₄ O ₂₅ : Eu-activated aluminate phosphor such as Eu, Tb, Sm, (Ba, Sr, Ca) MgAl ₁₀ O ₁₇ : Eu, Mn-activated Eu, Mn, etc. aluminate _{phosphors, SrGa 2 S 4: Ce,} CaGa 2 S 4: Ce activated thiogallate phosphor such as _{Ce, (Sr, Ca, Ba} , Mg) 10 (PO 4) 6 C l2: Eu such as Eu An activated halophosphate phosphor can be used.

  The phosphors of Examples 1 to 4 and Comparative Examples 1 to 3 were synthesized according to the procedure described below.

[Example 1]
Lanthanum nitride (LaN) was used as the La material, silicon nitride (Si ₃ N ₄ ) was used as the Si material, and cerium nitride (CeN) was used as the Ce material. As the fluxing agent, barium fluoride (BaF ₂ ) was used. Each raw material was weighed so that the molar ratio of each element was La: Si: Ce: Ba = 3: 6: 0.15: 0.25. Specifically, 5.69 g of LaN, 3.48 g of Si ₃ N ₄ , 0.29 g of CeN, and 0.54 g of BaF ₂ were weighed.

  The weighed raw materials were sufficiently pulverized and mixed in a dry manner to obtain a raw material mixture. The content of the fluxing agent in the raw material mixture was 5.4% by weight. The obtained raw material mixture was packed in a crucible and fired at 1500 ° C. for 10 hours in a reducing atmosphere to obtain a fired product. The obtained fired product was pulverized and treated with an acidic solution, then dispersed in water, recovered by solid-liquid separation, and dried to obtain a powdered phosphor.

[Example 2]
The fluorescence of Example 2 was obtained in the same manner as in Example 1 except that each raw material was weighed so that the molar ratio of each element was La: Si: Ce: Ba = 3: 6: 0.15: 0.35. The body was synthesized. The content of the fluxing agent in the raw material mixture was 7.4% by weight.

[Example 3]
The fluorescence of Example 3 was obtained in the same manner as in Example 1, except that each raw material was weighed so that the molar ratio of each element was La: Si: Ce: Ba = 3: 6: 0.15: 0.45. The body was synthesized. The content of the fluxing agent in the raw material mixture was 9.4% by weight.

[Example 4]
Each raw material is made of strontium fluoride (SrF ₂ ) instead of BaF ₂ as a fluxing agent so that the molar ratio of each element is La: Si: Ce: Sr = 3: 6: 0.15: 0.225 The phosphor of Example 4 was synthesized in the same procedure as in Example 1 except for weighing. The content of the fluxing agent in the raw material mixture was 3.6% by weight.

[Comparative Example 1]
Lanthanum nitride (LaN) was used as a raw material for La, silicon nitride (Si ₃ N ₄ ) was used as a raw material for Si, and cerium fluoride (CeF ₃ ) was used as a raw material for Ce. In Comparative Example 1, the fluxing agent used in the examples was not used. Each raw material was weighed so that the molar ratio of each element was La: Si: Ce = 3: 6: 0.15. Specifically, 5.97 g of LaN, 3.65 g of Si ₃ N ₄ and 0.38 g of CeF ₃ were weighed. Using the weighed raw materials, the phosphor of Comparative Example 1 was synthesized in the same procedure as Example 1.

[Comparative Example 2]
The phosphor of Comparative Example 2 was synthesized in the same procedure as in Example 4 except that magnesium fluoride (MgF ₂ ) was used instead of SrF ₂ as a fluxing agent. The content of the fluxing agent in the raw material mixture was 1.8% by weight.

[Comparative Example 3]
The phosphor of Comparative Example 2 was synthesized in the same procedure as Example 4 except that calcium fluoride (CaF ₂ ) was used instead of SrF ₂ as a fluxing agent. The content of the fluxing agent in the raw material mixture was 2.3% by weight.

The compositions of the phosphors of Examples 1 to 4 and Comparative Examples 1 to 3 were analyzed by ICP analysis (inductively coupled plasma emission analysis). Table 1 shows the composition (molar ratio) of each phosphor obtained based on the analysis result and the contents (ppm) of Ba, Sr, Mg, Ca, F and O in each phosphor. In addition, the sign “<” in Table 1 means that the Ba content is smaller than the numerical value indicated. From Table 1, it can be seen that the phosphors of Examples 1 to 3 contained 610 to 1800 ppm of Ba, whereas the Ba content in the phosphor of Comparative Example 1 was less than 10 ppm. Further, the phosphor of Example 4 using SrF ₂ as the fluxing agent contains 4400 ppm of Sr, and the phosphor of Comparative Example 2 using MgF ₂ as the fluxing agent contains 49 ppm of Mg and CaF as the fluxing agent. The phosphor of Comparative Example 3 using ₂ contained 5900 ppm of Ca.

  The average particle diameter Dm (μm) of the phosphors of the examples and comparative examples was measured by the pore electrical resistance method (electric detection zone method) based on the Coulter principle. Further, the chromaticity (x, y), luminance, and excitation wavelength of the phosphors of the examples and comparative examples were measured with a fluorescence spectrophotometer F-4500 (manufactured by Hitachi High-Tech). Table 2 shows the measurement results of the average particle diameter Dm (μm) and chromaticity (x, y) of each phosphor.

  The emission spectra and excitation spectra of the phosphors of Examples 1 to 4 and Comparative Examples 1 to 3 were measured. The results are shown in FIG. 2 and FIG. 2 and 3 show the results of Example 1 and Comparative Example 1 as representatives. The excitation spectrum shown in FIG. 3 is normalized by the intensity at a wavelength of 450 nm in order to make the difference between the phosphors easy to understand. From the measurement results of the emission spectrum, the luminance ratio was calculated for the emission luminance of the phosphors of the examples and comparative examples, with the luminance of comparative example 1 being 100%. Further, from the measurement results of the excitation spectrum, the first wavelength and the second wavelength at which the excitation intensity is 70% of the maximum value in the wavelength region of 400 to 510 nm are obtained for the phosphors of the examples and the comparative examples. The difference between the wavelength and the second wavelength was calculated. Table 2 shows the luminance ratio (%), the first wavelength (nm), the second wavelength (nm), and the difference between the first wavelength and the second wavelength (nm) of each phosphor. In Table 2, “wavelength difference” means a difference between the first wavelength and the second wavelength. Moreover, the minimum value of the excitation intensity in the wavelength region of 350 to 450 nm of the excitation spectrum was determined for the phosphors of the examples and comparative examples. Table 2 shows the relative intensity of the minimum value of the above-described excitation intensity when the maximum value of the excitation intensity at a wavelength of 450 nm is 100%.

(Particle size)
From Table 2, it can be seen that the phosphors of Examples 1 to 3 using BaF ₂ as the fluxing agent had a larger average particle size than the phosphor of Comparative Example 1 that did not use the fluxing agent. The phosphor of Example 4 using SrF ₂ as a fluxing agent had an average particle size equivalent to that of the phosphor of Comparative Example 1. The phosphors of Comparative Examples 2 and 3 using MgF ₂ or CaF ₂ as the fluxing agent had an average particle size smaller than that of the phosphor of Comparative Example 1.

(SEM measurement)
The SEM (scanning electron microscope) image of the phosphor of Example 1 is shown in FIG. 4, and the SEM image of Comparative Example 1 is shown in FIG. 4 and 5, it can be seen that the phosphor of Example 1 using BaF ₂ as a fluxing agent has a larger particle size compared to the phosphor of Comparative Example 1 that does not use the fluxing agent. . Similarly, it was confirmed by SEM measurement that the particle diameters of the phosphors of Examples 2 and 3 were larger than the particle diameter of the phosphor of Comparative Example 1.

(Emission spectrum)
2 that the emission spectrum peak of the phosphor of Example 1 was on the longer wavelength side than the emission spectrum peak of the phosphor of Comparative Example 1. FIG. Similarly, the emission spectrum peak of the phosphors of Examples 2 to 4 was on the longer wavelength side than the emission spectrum peak of the phosphor of Comparative Example 1. Furthermore, since the shift of the emission spectrum peak of the phosphors of Examples 1 to 4 to the long wavelength side was a shift toward a higher visibility, the luminance of the phosphors of Examples 1 to 4 should be increased. It is thought that was made. Moreover, from the measurement result of chromaticity, it turns out that the phosphor of Comparative Examples 1-3 produced the difference in the hue compared with the phosphor of Examples 1-4.

(Luminance)
From Table 2, it can be seen that the luminances of the phosphors of Examples 1 to 4 were higher by about 11 to 20% than the luminance of the phosphor of Comparative Example 1 in which no flux agent was used. The phosphor of the luminance of Comparative Examples 2 and 3 using MgF ₂ or CaF ₂ as a flux agent, it can be seen that were equal to or less than the luminance of the phosphor of Comparative Example 1.

(Excitation spectrum)
From Table 2, the phosphors of Examples 1 to 4 using BaF ₂ or SrF ₂ as the fluxing agent are compared with the phosphors of Comparative Example 1 that do not use these fluxing agents, and the first wavelength and the first wavelength. It can be seen that the difference between the two wavelengths has increased. The reason is that a part of the element of BaF ₂ or SrF ₂ used as the fluxing agent is replaced with La to widen the excitation spectrum of the phosphor, and the use of BaF ₂ or SrF ₂ as the fluxing agent. As a result, the crystallinity of the phosphor is improved, and as a result, the width of the excitation spectrum of the phosphor is broadened. On the other hand, the phosphors of Comparative Examples 2 and 3 using MgF ₂ or CaF ₂ as the fluxing agent have a smaller difference between the first wavelength and the second wavelength than the phosphor of Comparative Example 1. Recognize. The reason is that CeF ₂ used as a raw material of the phosphor of Comparative Example 1 also works as a fluxing agent, and the phosphors of Comparative Examples 2 and 3 using MgF ₂ or CaF ₂ as the fluxing agent are comparative examples. It is considered that the crystallinity was not improved as compared with the phosphor of No. 1. As mentioned above, it turned out that the fluorescent substance of Examples 1-4 can be excited by the excitation light over a wider wavelength range compared with the fluorescent substance of Comparative Examples 1-3. Table 2 also shows that the phosphors of Examples 1 to 4 have a minimum excitation intensity of 50% or more, with the maximum excitation intensity being 100%. Further, in Examples 1 to 3 using BaF ₂ as a fluxing agent, it can be seen that the minimum value of the excitation intensity was 60% or more, with the maximum value of the excitation intensity being 100%. From this, it turned out that the fluorescent substance of Examples 1-4 can be excited more strongly by excitation light compared with the fluorescent substance of Comparative Examples 1-3.

  From the above results, the phosphors of Examples 1 to 4 have higher luminance than the phosphors of Comparative Examples 1 to 3, can be excited by light in a wide wavelength range, and have excellent emission characteristics. I found it.

  Furthermore, the light emitting devices of Comparative Example 4 and Examples 5 to 7 were produced using the phosphors of Comparative Example 1 and Examples 1 to 3, respectively. The light emitting devices of Comparative Example 4 and Examples 5 to 7 were surface mounted light emitting devices as shown in FIG. In each of the examples and comparative examples, a nitride semiconductor light emitting element that emits light having an outer dimension of 500 μm × 290 μm and a peak wavelength of 450 nm was used as an excitation light source, and a silicone resin was used as a sealing member. The above-described light emitting element is disposed in the recess formed in the package of the light emitting device, and the silicone resin containing the phosphor of any one of Comparative Example 1 and Examples 1 to 3 is placed in the recess so as to cover the light emitting element. By filling, the light emitting devices of Comparative Example 4 and Examples 5 to 7 were produced. The light emitting devices of Comparative Example 4 and Examples 5-7 thus obtained were driven under the conditions of a forward current of 150 mA and a forward voltage of 3.3 V, respectively, and the luminous flux was measured. The luminous flux of the light emitting device was measured using an integral type total luminous flux measuring device. From the measurement results of the luminous flux, the luminous flux ratio was calculated for the light emitting devices of the examples and the comparative examples, where the luminous flux of the comparative example 4 was 100. The results are shown in Table 3 and FIG. FIG. 6 shows the emission spectra of the light emitting devices of Comparative Example 4 and Example 5 as representatives. As shown in Table 3, the light emitting devices of Examples 5 to 7 using the phosphors of Examples 1 to 3 are higher than the light emitting device of Comparative Example 4 using the phosphor of Comparative Example 1. It was confirmed that the luminous flux value was shown. In addition, as shown in FIG. 6, it was confirmed that the light emitting device of Example 5 had higher emission intensity than the light emitting device of Comparative Example 4 in the wavelength region including green. Similarly, it was confirmed that the light emission intensity of the light emitting devices of Examples 6 and 7 was higher than that of the light emitting device of Comparative Example 4.

  The phosphor according to the present invention is a white illumination light source, an LED display, a backlight light source, a traffic light, an illumination switch, various sensors, and various indicators that are particularly excellent in light emission characteristics using a blue light emitting diode or an ultraviolet light emitting diode as a light source Etc. can be suitably used.

DESCRIPTION OF SYMBOLS 100 Light-emitting device 10 Light-emitting element 20, 30 Lead electrode 40 Package 50 Sealing member 60 Conductive wire 70 Phosphor

Claims (10)

A phosphor represented by a general formula La _x Ce _y Si ₆ N _{8 + x + y} (where 2.0 ≦ x ≦ 3.5, 0 <y ≦ 1.0),
Containing 10 to 10,000 ppm of Ba and / or Sr;
In the wavelength region of 400 to 510 nm, there are a first wavelength and a second wavelength at which the excitation intensity becomes 70% of the maximum value, the second wavelength is longer than the first wavelength, and the first wavelength and the second wavelength A phosphor having a wavelength difference of 70 nm to 86 nm.   The phosphor according to claim 1, wherein a difference between the first wavelength and the second wavelength is 80 nm or more.   The phosphor according to claim 1 or 2, wherein the minimum value of excitation intensity in the wavelength region of 350 to 450 nm is 50% or more of the maximum value of excitation intensity in the wavelength region of 400 to 510 nm. A phosphor represented by a general formula La _x Ce _y Si ₆ N _{8 + x + y} (where 2.0 ≦ x ≦ 3.5, 0 <y ≦ 1.0),
Containing 10 to 10,000 ppm of Ba and / or Sr;
The phosphor whose minimum value of the excitation intensity in the wavelength region of 350 to 450 nm is 50% or more and 66.3% or less of the maximum value of the excitation intensity in the wavelength region of 400 to 510 nm.   The phosphor according to any one of claims 1 to 4, comprising 500 to 10,000 ppm of Ba and / or Sr.   The phosphor according to any one of claims 1 to 5, which contains 10 to 10,000 ppm of F.   The phosphor according to any one of claims 1 to 6, wherein the phosphor has an average particle diameter of 15 to 40 µm.   A light-emitting device provided with the excitation light source which emits the light of a blue region from an ultraviolet region, and the fluorescent substance of any one of Claims 1-7. A method for producing a phosphor represented by the general formula La _x Ce _y Si ₆ N _{8 + x + y} (where 2.0 ≦ x ≦ 3.5, 0 <y ≦ 1.0),
A simple substance of La, Ce and Si, oxide, nitride, carbonate, phosphate, silicate or halide is weighed so as to have a stoichiometric ratio of the composition of the phosphor, and at least as a fluxing agent. Obtaining a raw material mixture by grinding and mixing with BaF ₂ and / or SrF ₂ ;
Firing the raw material mixture in a reducing atmosphere to obtain a fired product;
Crushing the fired product to obtain a powdered phosphor.   The method of Claim 9 whose content of the flux agent in the said raw material mixture is 0.01-15.0 weight%.

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